Taxi drivers are a marginalized, large, growing, minority male population with multiple health risks. In New York City (NYC) alone, there are over 50,000 yellow taxi drivers and a similar number of livery drivers. A large majority, 94%, are immigrants, mainly originating from India, Bangladesh, Pakistan, the Dominican Republic, Haiti, and West African countries. Taxi drivers are at great risk for poor health, with increased cardiovascular disease (CVD) and overlapping cancer risk, due to an extremely sedentary lifestyle, high stress, diet, environmental exposures, poor health care access, and safety concerns. Studies in Japan show a higher taxi driver prevalence of myocardial infarction, multi-vessel disease and CVD risk factors (body mass index (BMI), diabetes, smoking, low-density lipoprotein cholesterol levels, and hypertension. Sedentary time is associated with increased CVD mortality, higher triglycerides and insulin resistance, and lower high-density lipoprotein levels, and with increased colon and lung cancer risk. The taxi driver community, while facing tremendous health risk, also has notable assets within it to facilitate driver health. Ten percent of a sample of NYC taxi drivers were teachers in their home countries and there are numerous drivers who held health-related jobs before immigrating. The drivers, through their existing social networks, exchange information about traffic, food vendors, cricket and soccer games, and other news. Their networks have the potential to disseminate health risk reduction information and strategies. Over the past three years, the NIMHD-funded R24 program, the Taxi Network, has developed a robust community-based participatory research (CBPR) infrastructure, which it has utilized to conduct a number of path-breaking pilot translational CBPR research projects. The overall goal of the current Taxi Network proposal, Taxi STEP (Social networks, Technology, and Exercise through Pedometers), is to expand the robust Taxi Network CBPR infrastructure, which taps into the many assets of the taxi driver community, to work towards the elimination of health disparities in this large at-risk group. Taxi STEP is the first full project of the Taxi Network, and is a physical activity promoting, and hence a CVD/cancer risk reduction, study developed through an ongoing, iterative process with the community, built upon extensive preliminary work in this area. Taxi STEP will use an Intervention Mapping approach to effect an increase in physical activity among drivers, and secondarily other healthful behaviors, and will be evaluated using the RE- AIM framework. A randomized controlled trial (RCT) will be used to measure the effectiveness of four different approaches to increasing step counts. The 4 arms include: 1) Health Fairs (HF) + pedometers (PED) (Control); 2) HF/PED + text messaging (mHealth); 3) HF/PED + social network support (SNS); 4) HF/PED + mHealth + SNS. The costs of each approach will also be determined, and a plan to disseminate best practices to the North American taxi driver population will be developed.